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<p class="purpose">Recording where fragments of text originally came from.</p>

<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>&#167;1. </b>Inter code sometimes needs to contain fragments of not-yet-parsed Inform 6
syntax code, in the form of <span class="extract"><span class="extract-syntax">SPLAT_IST</span></span> and <span class="extract"><span class="extract-syntax">INSERT_IST</span></span> instructions. In order
for it to be possible to relate errors in those fragments to the original text
files they came from, we need to record their "provenance".
</p>

<p class="commentary">This is only a wrapper for saying something like "line 17 in <span class="extract"><span class="extract-syntax">whatever.txt</span></span>".
Line numbers count from 1 at the top of a text file.
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">textual_filename</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">line_number</span><span class="plain-syntax">;</span>
<span class="plain-syntax">} </span><span class="reserved-syntax">text_provenance</span><span class="plain-syntax">;</span>
</pre>
<ul class="endnotetexts"><li>The structure text_provenance is accessed in 4/tpc8 and here.</li></ul>
<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>&#167;2. </b>This provides a "don't know, or, it didn't come from a text file, I made it up"
value:
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> </span><span class="function-syntax">Provenance::nowhere</span><button class="popup" onclick="togglePopup('usagePopup1')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup1">Usage of <span class="code-font"><span class="function-syntax">Provenance::nowhere</span></span>:<br/>The Insert Construct - <a href="4-tic.html#SP6">&#167;6</a><br/>The Provenance Construct - <a href="4-tpc8.html#SP7">&#167;7</a><br/>The Splat Construct - <a href="5-tsc.html#SP6">&#167;6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">void</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> </span><span class="identifier-syntax">nowhere</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">nowhere</span><span class="plain-syntax">.</span><span class="element-syntax">textual_filename</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">nowhere</span><span class="plain-syntax">.</span><span class="element-syntax">line_number</span><span class="plain-syntax"> = </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">nowhere</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>

<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Provenance::is_somewhere</span><button class="popup" onclick="togglePopup('usagePopup2')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup2">Usage of <span class="code-font"><span class="function-syntax">Provenance::is_somewhere</span></span>:<br/><a href="3-tp.html#SP4">&#167;4</a>, <a href="3-tp.html#SP5">&#167;5</a>, <a href="3-tp.html#SP6">&#167;6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> </span><span class="identifier-syntax">where</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">Str::len</span><span class="plain-syntax">(</span><span class="identifier-syntax">where</span><span class="plain-syntax">.</span><span class="element-syntax">textual_filename</span><span class="plain-syntax">) &gt; </span><span class="constant-syntax">0</span><span class="plain-syntax">) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>&#167;3. </b>Composing:
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> </span><span class="function-syntax">Provenance::at_file_and_line</span><button class="popup" onclick="togglePopup('usagePopup3')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup3">Usage of <span class="code-font"><span class="function-syntax">Provenance::at_file_and_line</span></span>:<br/>The Insert Construct - <a href="4-tic.html#SP6">&#167;6</a><br/>The Provenance Construct - <a href="4-tpc8.html#SP7">&#167;7</a><br/>The Splat Construct - <a href="5-tsc.html#SP6">&#167;6</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">file</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">line</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> </span><span class="identifier-syntax">somewhere</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">somewhere</span><span class="plain-syntax">.</span><span class="element-syntax">textual_filename</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Str::duplicate</span><span class="plain-syntax">(</span><span class="identifier-syntax">file</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="identifier-syntax">somewhere</span><span class="plain-syntax">.</span><span class="element-syntax">line_number</span><span class="plain-syntax"> = </span><span class="identifier-syntax">line</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">somewhere</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>&#167;4. </b>Decomposing:
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">Provenance::get_line</span><span class="plain-syntax">(</span><span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> </span><span class="identifier-syntax">where</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="3-tp.html#SP2" class="function-link"><span class="function-syntax">Provenance::is_somewhere</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">where</span><span class="plain-syntax">)) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">where</span><span class="plain-syntax">.</span><span class="element-syntax">line_number</span><span class="plain-syntax">;</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="constant-syntax">0</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>

<span class="identifier-syntax">filename</span><span class="plain-syntax"> *</span><span class="function-syntax">Provenance::get_filename</span><span class="plain-syntax">(</span><span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> </span><span class="identifier-syntax">where</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="3-tp.html#SP2" class="function-link"><span class="function-syntax">Provenance::is_somewhere</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">where</span><span class="plain-syntax">))</span>
<span class="plain-syntax">        </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">Filenames::from_text</span><span class="plain-syntax">(</span><span class="identifier-syntax">where</span><span class="plain-syntax">.</span><span class="element-syntax">textual_filename</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>&#167;5. </b>Altering in place:
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Provenance::set_line</span><span class="plain-syntax">(</span><span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">where</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">lc</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">where</span><span class="plain-syntax">) &amp;&amp; (</span><a href="3-tp.html#SP2" class="function-link"><span class="function-syntax">Provenance::is_somewhere</span></a><span class="plain-syntax">(*</span><span class="identifier-syntax">where</span><span class="plain-syntax">)))</span>
<span class="plain-syntax">        </span><span class="identifier-syntax">where</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">line_number</span><span class="plain-syntax"> = </span><span class="identifier-syntax">lc</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>

<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Provenance::advance_line</span><span class="plain-syntax">(</span><span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> *</span><span class="identifier-syntax">where</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">by</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">where</span><span class="plain-syntax">) &amp;&amp; (</span><a href="3-tp.html#SP2" class="function-link"><span class="function-syntax">Provenance::is_somewhere</span></a><span class="plain-syntax">(*</span><span class="identifier-syntax">where</span><span class="plain-syntax">)))</span>
<span class="plain-syntax">        </span><span class="identifier-syntax">where</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">line_number</span><span class="plain-syntax"> += </span><span class="identifier-syntax">by</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>&#167;6. </b>Writing to text:
</p>

<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">Provenance::write</span><button class="popup" onclick="togglePopup('usagePopup4')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup4">Usage of <span class="code-font"><span class="function-syntax">Provenance::write</span></span>:<br/>The Insert Construct - <a href="4-tic.html#SP5">&#167;5</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">OUTPUT_STREAM</span><span class="plain-syntax">, </span><span class="reserved-syntax">text_provenance</span><span class="plain-syntax"> </span><span class="identifier-syntax">at</span><span class="plain-syntax">) {</span>
<span class="plain-syntax">    </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="3-tp.html#SP2" class="function-link"><span class="function-syntax">Provenance::is_somewhere</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">at</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax">        </span><a href="3-iitf.html#SP11" class="function-link"><span class="function-syntax">TextualInter::write_text</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">OUT</span><span class="plain-syntax">, </span><span class="identifier-syntax">at</span><span class="plain-syntax">.</span><span class="element-syntax">textual_filename</span><span class="plain-syntax">);</span>
<span class="plain-syntax">        </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">" %d"</span><span class="plain-syntax">, </span><span class="identifier-syntax">at</span><span class="plain-syntax">.</span><span class="element-syntax">line_number</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> {</span>
<span class="plain-syntax">        </span><span class="identifier-syntax">WRITE</span><span class="plain-syntax">(</span><span class="string-syntax">"&lt;nowhere&gt;"</span><span class="plain-syntax">);</span>
<span class="plain-syntax">    }</span>
<span class="plain-syntax">}</span>
</pre>
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